Radio signaling



April 19, 1932. l EN 1,854,448

RADIOS IGNALIQNG Filed Sept. 1'7, 1928 2 Sheets-Sheet l -/fi a /5 5 6will}? WINK 1.. COHEN 1,854,448

RAD'IOSIGNALING Filed Sept. 17, 1928 April 19, 1932.

2 Shets-Sheet 2 uuonn Jr 9 7* Patented Apr. 19, 1932 STATES UNITE PATENTonion RADIO SIGNALING Application filed September 1'7, 1928. Serial No.306,577.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1928; 3700. G. 757) The invention described herein may be manufactured and usedby or for the Government for governmental purposes, without the paymentto me of any royalty thereon.

1 This invention relates to the art of radio signaling and particularlyto improvements in receiving systems of radio signals.

The invention has for its object an improvement in methods and means forthe reception of radio signals by which a high degree of selectivity andfreedom from interfering disturbances are secured.

This invention is an extension of the inventions covered by my patentapplications relating to radio signaling, serially numbered 293,608;294,742; 299,386 and 303,087 and filed July 18, July 23, August 13, andAugust 30, 1928 respectively. The same principles are utilized in thisinvention but in a modified form securing thereby additionalimprovements in the selective reception of radio signals.

Particular reference may be had to my copending patent application, Ser.Number 293,608 filed July 18, 1928, in which a method for the receptionof radio signals is disclosed which consists in interposing a waveconductor between the antenna and the receiving circuit system, the waveconductor being one of distributed inductance and capacity andadjustable in relation to the frequency of the signals desired toreceive. It is shown that by placing a receiving circuit system in inductive relation to the wave conductor and suitably adjusting both thereceiving circuit system and the wave conductor, a high degree ofselectivity in the reception of radio signals is obtained.

In this invention a modification is intro- 40 duced which consists inthe use of two wave conductors placed in inductive relation to eachother; one of the wave conductors is connected to the antenna and theother wave conductor is connected to the receiving circuit system. Bythe suitable adjustment of the invention willappear evident from thedescription and discussion of the accompanying drawings which showtypical embodiments of the invention.

In the drawings:

Fig. 1 is a diagrammatic view of the embodiment of the invention showingtwo coupled wave conductors, one connected to the antenna and the otherto a receiving circuit system. r

Fig. 2 is-a modification in which three wave conductors are used, theantenna connecting to two wave conductors in series and the receivingcircuit coupled through a wave conductor to the second of the twoantenna wave conductors. I

Fig. 3 is a modification of Figure 1 in that the antenna is groundedthrough an impedance; I

Figure 4 shows a modification in which the antenna is grounded throughanimpedance and also a nodal point of the antenna wave conductor groundedthrough an impedance.

Figure 5 is similar to Fig. 3, showing however, a tuned circuit as thegrounded impedance of the antenna;

Figure 6 is a modification of Fig. 4 showing tuned circuits in place ofthe two grounded impedances of Fig. 4.

Having particular reference to the drawings in which the same numbersdesignate similar parts in all of the drawings in Figure 1 the antennadesignated by 1 is connected to coil 2 which is placed in proximity tometal plate 3 which is grounded at 4 through lead 7 The coil 2 togetherwith the grounded metal plate 3 forming a wave conductor, that is aconductor of distributed inductance and capacity on which a wavedevelopment may be effected by an incoming signal acting on the antenna.The distributed capacity of the wave conductor is varied by varying thedistance separation of the coil from the metal plate which may beaccomplished in various ways. The wave conductor 5, 6, 4 which is ofexactly the same form as the wave conductor 2, 3, 4, is placed ininductive relation to the latter. It is preferable to parallel the twowave conductors and adjust the separation between them until the bestresults are obtained. The receiving circuit system 9 is connected toterminal 16 of wave conductor 5, 6, 4. I11 the practical operation ofthis circuit system an adjustment is eifected by varying the separationdistances of coils 2 and 5 from their respective grounded metal plates 3and 6. The adjustment of wave conductor 2, 3, 4 is somewhat morecritical but in any case the point of best adjustment is evidenced bythe intensity of the signals in the receiver 9. Theory would indicatethat the adjustments of the wave conductors should be for a quarter wavelength of the signals desired to receive. I shall accordingly designatethe system shown in Figure 1 as a quarter wave length system.

It is preferable to have in this arrangement the two wave conductors ofthe same design but it is not essential. The coils of the two waveconductors may be of different dimensions and different number of turnsof wire on each, provided that they are so designed that each can beadjusted for the particular range of signal frequencies for which theiruse is intended. The letters A and G on the receiver box 9 indicate theantenna and ground connections respectively of the receiver. In thearrangements disclosed in this invention the receiver may or may not begrounded, that is the ground connection G may or may not be connected toground 4.

The modification shown in Figure 2 consists in interposing an additionalwave conductor 10, 11, 4 in the antenna circuit. This wave conductor isadjustable to approximately double the electrical wave length of waveconductors 2, 3, 4 so that together it forms a three quarter wave lengthconductor. The wave conductor 5, 6, 4 is placed in inductive relation towave conductor 2, 3, 4 as in the arrangement shown in Figure 1. Thisoffers a somewhat additional improvement in the matter of selectivity.

The arrangement shown in Figure 3 differs from Figure 1 only in that theantenna is grounded at 4 through a variable impedance 12.; that is atthe junction point 13 where the antenna connects to the wave conductor2, 3, 4 a grounded connection is made through a variable impedance. Thisimpedance 12 may be in the form of a variable resistance, variableinductance, variable condenser or a combination of these elements. Inthe pendapplications referred to above the theory of the circuit wasdiscussed and it was pointed out that when the wave conductor 2, 3, 4 isproperly adjusted to approximately a quarter or an. odd multiple ofquarter wave lengths hen for. a signal of. that wave length for which.it is in adjustment, the junction point lgtis at a minimum potential,practically zero potential, if the resistance of the wave con-- ductor'is small and hence grounding that point through an impedance has verylittle, if any, effect in impairing the. efficiency of reception ofsignals of that particular frequency. For signals, however, of otherfrequencies the junction point 13 is no longer at zero value and hence aconsiderable amount of the signal energy will leak away to ground atthat point. This therefore offers an additional means for increasing theselectivity of reception. This is of particular advantage in theelimination of irregular disturbances such as static or otherinterferences.

The modification shown in Figure 4 is an extension of the arrangement ofFigure 2 in that a three quarter wave length conductor is used in theantenna circuit, and impedance leaks are connected to ground at the twonodal points 13 and 15 which contribute much to the increase in theselectivity of signal reception; all of which is in accordance with thetheory given in my pending applications referred to and which is amplysupported and corroborated by experimental tests.

The circuit system of Fig. 5 difiers from that of Figure 3 in that theimpedance 12, through which the antenna is grounded is in the form of atuned loop circuit which consists of an inductance 17 in parallel withthe variable condenser 18. By suitably tuning this circuit, a stillfurther increase in the selectivity of the system is obtained.

The modification shown in Figure 6 differs from that of Figure 4 in thatthe impedances 12 and 14 of that figure are replaced by tuned circiuts12 and 14, each consisting of an inductance and a variable condenser inparallel; that is the antenna is grounded at 13 through the tunedcircuit 12 which consists of inductance l7 and a variable condenser 18.Also the nodal point 15 is grounded through the tuned circuit 14 whichconsists of an inductance 19 and a variable condenser 20. By properlytuning the circuits l2 and 14' and suitably adjusting the waveconductors a remarkably high degree of selectivity in the reception ofradio signals is ob tained.

I claim:

1. In a system for the reception of radio signals, comprising anantenna, and two adjustable wave conductors in inductive relation toeach other, one of said wave conductors being connected to said antenna,and the other of said wave conductors being connected to a receivingcircuit system provided with means for detection and amplification, andmeans for adjusting each of said wave conductors to a quarter wavelength of the signals desired to be received.

2. In a system for the reception of radio signals, comprising anantenna, and two adjustable wave conductors in inductive relation toeach other, one of said wave conduc tors being connected to saidantenna, and the other of said wave conductors being connected to areceiving circuit system provided with means for detect-ion andamplification, means for adjusting said wave conductor which isconnected to said antenna to an odd multiple of quarter wave lengths andmeans for adjusting said other wave conductor to a quarter wave lengthof the signal desired to be received.

3. In a system for the reception of radio signals comprising an antenna,two adjustable wave conductors in inductive relation to each other, oneof said wave conductors being connected to said antenna and means foradjusting the same to approximately three quarter wave lengths of thedesired signal, grounded impedance leaks connected at the junction pointof connection of said wave conductor to said antenna and at the nodalpoint on said wave conductor, which is approximately half wave lengthdistance from said junction point, the other of said wave conductorsbeing connected to a receiving circuit system provided with means fordetection and amplification.

4. In a system for the reception of radio signals comprising an antenna,two adjustable wave conductors in inductive relation to each other, oneof said wave conductors being connected to said antenna and means foradjusting the same to approximately three quarter wave lengths of thedesired signal,

grounded impedance leaks connected at the junction point of connectionof said wave conductor to said antenna and at the other nodal point ofsaid wave conductor, the other of said wave conductors being connectedto a receiving circuit system provided with means for detection andamplification, each of said impedances being in the form of a tuned loopcircuit comprising an inductance and capacity in parallel.

5. In a system for the reception of radio signals comprising an antenna,two adjustable wave conductors in inductive relation to each other, oneof said wave conductors being connected to said antenna and means foradjusting the same to approximately three quarter wave lengths of thedesired signal, grounded impedance leaks connected at the junction pointof connection of said wave conductor to said antenna and at the othernodal point of said wave conductor, the other of said wave conductorsbeing connected to a receiving circuit system provided with means fordetection and amplification, each of said impedances being in the formof a tuned loop circuit comprising an inductance and capacity inparallel, said tuned loop circuits being tuned for the frequency of thedesired signals.

6. In a system for the reception of radio signals, comprising anantenna, and two adjustable wave conductors in inductive relation toeach other, one of said wave conductors being connected to said antenna,and the other of said wave conductors being connected to a receivingcircuit system provided with nals.

In testimony whereof I affix my signature.

LOUIS COHEN.

